Total depth after etching is 21.864 um
Calculated remaining resist as 7.06um, indicating an erosion of 1.68um in 10 minutes of etching
This equates to an erosion rate of 168 nm/min
The etch depth of 14.80um in 10 mins indicates an etch rate of 1480.0nm/min
The selectivity is therefore 8.83:1